It has been known for many years to make a type of chair that has slats and a fabric hinge, such that the chair can be rolled up. Chairs of this type are shown, for example, in U.S. Pat. No. 2,001,252 issued to Johnson on May 14, 1935 and in U.S. Pat. No. 5,100,203 issued Mar. 31, 1992 to Novak.
In this kind of chair there are, typically, three pieces of webbing, generally made of canvas, with pouches, or pockets, sewn in them. One piece of webbing forms the hinge of the chair, and has pockets on both sides. A number of slats are provided, half of the slats being used for the seat of the chair, and half of the slats being used for the back. Each of the slats has one end that is secured in a pocket of the hinge piece of webbing. The other end of each slat is secured in a pocket of one of the other pieces of webbing. The top and bottom edges of the chair are formed by these other pieces of webbing, and the relationship of the sewn pockets is such as to maintain the relative, generally parallel positions of the adjacent slats of the back and seat portions of the chair. The opening of the chair is limited by a pair of straps, one each on either side of the chair, that extend from the outermost seat slat on each side to the outermost back slat on each side. These straps are connected, generally, to the respective slats at or near the end pieces of webbing.
When a person sits on the seat portion of the chair, the limit of opening of the back relative to the chair is determined by the length of the straps. The slats draw in around the body, and tend to provide stiffening to support the user's back. A slat chair of this type, of the proper size, is intended to hug the body quite comfortably. Chairs of this nature are generally light enough to be carried easily, whether to the beach, or to sit in bleachers, or to use as a camping or fishing chair.
These chairs have the advantage of being foldable, and, when folded, have the ability to be rolled up into a relatively small package. Portable folding chairs are known that employ nylon covered padding for the seat and back portions of a folding chair, with battens placed along opposite sides of the back portion, inside the nylon covering. These chairs are not entirely satisfactory. First, when used at the beach, for example, the nylon does not permit as much air movement around the body as an array of slats with spaces between them, and, depending on the user's taste, may not be found adequately comfortable against the skin or a bathing suit. Second, in two types of chair, the foam padding used in the back and seat is not as stiff as an array of slats, and consequently does not provide the same vertical back support. In one of those two types, while the back is not as stiff as an array of slats, it is too stiff to facilitate easy rolling up of the chair in the rolling direction, that is, the direction generally perpendicular to the slats.
The present inventors have also noted a number of disadvantages with other existing examples of the slat type of chairs. First, according to the commentary in U.S. Pat. No. 5,100,203 the chair disclosed in U.S. Pat. No. 2,001,252 either allowed the slats to float free in the pockets, or employed rivets to fasten the slats to the pockets. The use of rivets was thought to weaken the slats. In U.S. Pat. No. 5,100,203 Novak used divergent closure staple means which penetrated inwardly from the outside of the web pieces, but did not pierce the inside wall of the web piece.
The present inventors have found that metal fasteners tend to work in the web, or fabric, and may rip out. Alternatively, when staples are used, they may catch on the ends of the fingers, or on finger nails, pierce the skin, or catch on clothing, which is not always an enjoyable experience for the user. Further, depending upon the type of staple or rivet used, the staple may tend to oxidize. In the worst case, with mild steel staples in a sea salt atmosphere, rust forms on the staples, and unsightly rust streaks appear on the webbing. Rust may tend to rot the material, and the material may tend to tear away from the rusted staple.
A third problem is that even when rivets or staples are used, the slats tend to work in the pockets, which may result in unnecessary wear to the chair, and may also result in the slats not maintaining the desired relationship one to another, with the chair becoming more shifty than may be desired.
A fourth problem is caused by a combination of factors. First, canvas material is available in standard widths. A chair of this nature is generally such that a manufacturer might tend to think first of trimming manufacturing costs to the maximum extent possible. In one type of chair presently sold, it appears that the webbing pieces have been cut to maximise the number of pieces that can be obtained from a standard width. This chair has several 5/8" slats, with roughly 1/2" clearance between adjacent slats. The overall unstretched developed width of the slat array is roughly 143/4". When used by an average sized, or larger, North American adult, the ends of the outer-most slats may tend to dig into the user's sides. This may cause discomfort, first from lateral pinching of the body generally, and second from the quite uncomfortable experience of the ends of the outer back slats digging into the ribs.
The present inventors have noted that this discomfort can be reduced or eliminated by one or more measures. First, a greater use of material allows the slats to be more widely separated. This results in a relatively minor increase in the amount of material used, and in the weight of the chair, yet permits average, or larger, persons to sit more comfortably. It is also a more efficient structure, since the weight that can be contained within the chair increases without a need to increase the size, number, or weight of the slats. That is, the ratio of the load per unit weight of the chair improves.
This can be further enhanced by using a heavy or very heavy grade of canvas, and folding it to double the thickness, or by lining the pockets with cushioning material, or both.
Further still, by using a heavy grade of material, by folding it to double its thickness, and by sewing the pockets slightly undersized, the slats can be located more snugly in the pockets formed in the end pieces and in the hinge. Conceptually this is akin to an interference fit. A tight fit discourages the slats from working within the material as easily. This tends to maintain the slats in their desired orientation relative to each other.
The use of a water proof glue has the advantage of not relying upon a metal fastener that can oxidise and cause streaking. Further, unlike rivets or staples, which tend to approximate a point contact, glue can be applied along a line of contact, or over a wider area generally, such that the web stresses that are transferred to and from the slats tend not to be as highly concentrated at a single point or points.
Continuing with their efforts to reduce the tendency of the outer corners of the outermost slats to dig into the ribs, the inventors have eased the corners of the slats. That is, they have mitred the outer corners, and then made a smoothly radiused tip. Further, the inventors have introduced a smoothly radiused, obliquely angled, oblong slot into the outermost slats. The stay strap extends, in use, to wrap around the outer most slats at an angle. As the material is wrapped around the back of the slat it continues on the angle. In previous chairs a staple or rivet was driven through the strap on the to hold it in place. But, the inventors continue to wrap the strap through the slot, and then up the front side of the slat at an angle more or less perpendicular to the chamfer. The strap is carried over the chamfer and back down the rear side of the slat, where it can be secured to the slat and to itself with glue. The folded over end of the strap can be tucked under itself. Without the slot the strap would have to meet the slat at a point closer to the hinge.
In some conditions, such as ice fishing, or watching sporting events in the fall, it may be desirable to be able to insert an additional cushion, or a heating pad, in either the seat or the back of such a chair.
Finally, in some instances may be desirable to taper the back rest, according to a user's body shape. Differing the amount of webbing between adjacent slats does not generally alter the tendency of the slats to roll up in a generally cylindrical manner when not in use.